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The Indian Dental Academy is the Leader in

continuing dental education , training dentists

in all aspects of dentistry and offering a wide

range of dental certified courses in different

formats.

Indian dental academy provides dental crown &

Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit

www.indiandentalacademy.com ,or call
0091-9248678078

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  • Head fold begins to form,floor of the stomato is the buccopharyngeal mem,head represents the bulging of the brain while the pericardium occupies the future thorax,neckis formed by the elongation b/w this two,mainly by the appearance of a series of mesodermal thickenings in the cranial most part of the fore gut –pharyngeal archs. <br />
  • Coronal section through cranial part of foregut before & after formation of the pharyngeal arches .embryo showing limb buds <br />
  • Structures present in the arch <br />
  • derivatives <br />
  • Before formation of frontonasal process & after formation. Dev of face,fromation of max &man process.mandibular arch forms the lateral wall of the stomatodium,gives a bud like st.max process from its dorsal end,grows ventromedially.grows to meet at the midline forming the lower margin of the stomatodium,giving rise to the lower lip &mand. <br />
  • Blastema- a group of cells giving rise to a new organ or part either in normal dev or in regeneration.they are situated at a relatively large distance. The first evolves to contribute to the formation of condylar cartilage,the aponeurosis of the external pterygoid muscle, the disc,& the capsular elements of the lower joint . The second develops into the articular st of the upper level. <br />
  • Pterygoid fovea- attachment of the inf. Head of the lateral pterygoid & is situated on the ant part of the neck below the articular surface. <br />
  • The process involves mineralization of the cartilage matrix & subsequent degeneration of chondrocytes.osteo blasts deposit woven bone around the template of calcified cartilage –mature bone <br />
  • Tmj lat view <br />
  • Chondrotin sulphate –presence suggest that the disc is subjected to compressive loads. <br />
  • Cross bite,deepbite.trauma,emotional stress,systemic condition,bruxism <br />
  • Mild physical therapy,flat appliance,4-6weeks <br />
  • 5degr of change can alter the condyle position <br />

Tmj ....a basic review  /certified fixed orthodontic courses by Indian   dental academy Tmj ....a basic review /certified fixed orthodontic courses by Indian dental academy Presentation Transcript

  • www.indiandentalacademy.com
  • INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  • •INTRODUCTION •CLASSIFICATION OF JOINTS •EVOLUTION OF TMJ & JAWS •DEVELOPMENT OF TMJ •MUSCLES OF MASTICATION •TMJ ANATOMY •HISTOLOGY •BIOMECHANICS OF TMJ •EXAMINATION OF TMJ •DIAGNOSTIC IMAGING •TMD •CONCLUSION www.indiandentalacademy.com •REFERANCES
  • INTRODUCTION www.indiandentalacademy.com
  • Why study TMJ as an orthodontist The TMJ influences the function, esthetics, & structural harmony of the teeth, dentition, face and thus a person in total. Therefore an understanding of the anatomy , physiology, biomechanics etc., of the masticatory www.indiandentalacademy.com system is very much necessary. ?
  • The masticatory system or the somatognathic system consists of the skull bones, mandible, hyoid, clavicle, sternum; the masticatory muscles,& ligaments; the dentoalveolar complex; the vascular, neural & lymphatics and the TMJ. The masticatory system is responsible for CHEWING, DEGLUTATION, SPEECH, etc………… www.indiandentalacademy.com
  • Classification of Joints 1.SYNARTHROSIS: (i) FIBROUS JOINTS A: SUTURES (collagenous sutural ligament) B: SYNDESMOSES (collagenous ligament + elastic fibrous tissue) C: GOMPHOSES (complex fibrous & cellular periodontium) (ii) CARTILIGENOUS JOINT A: SYNCHONDROSIS (hyaline cartilage) B.SYMPHYSES (hyaline cartilage+ fibrocartilagenous disk) (iii) SYNOSTOSES (rigid bony unions) 2. DIARTHROSES: SYNOVIAL JOINT (Synovial fluid present between articulating surfaces) www.indiandentalacademy.com
  • Classification of Joints •FIBROUS •CARTILAGENOUS •PRIMARY •SECONDARY •SYNOVIAL www.indiandentalacademy.com
  • Temperomandibular joint “Nothing is more fundamental in treating patients than knowing the anatomy.” - Okeson Most human bones are connected to each other by JOINTS or ARTICULATIONS. Some of them being mobile while being immobile. In the mobile joints the surfaces are covered by cartilage & fibrous tissue forming a capsule.the inner lining cells secrete SYNOVIAL fluid that allows freedom for the joint to move. www.indiandentalacademy.com
  • •TEMPEROMANDIBULAR JOINT IS A COMPOUND, BICONDYLAR, GINGLIMO-ARTHROIDAL, ELIPSOIDAL, SYNOVIAL JOINT. •IT IS A WEIGHT BEARING JOINT. IT BEARS ABOUT 500N OF FORCE. •THE TMJ IS LOADED MORE IN THE NON WORKING CONDITION THAN IN WORKING SIDE. •TMJ IS ONE OF THE MOST COMPLICATED JOINTS IN THE BOBY AND IT IS FORMED BY THE ARTICULATION OF THE MANDIBLE TO THE CRANIUM. •THE MANDIBULAR CONDYLAR HEADS FITS INTO THE GLENOID FOSSAE OF THE SQUAMOUS PART OF THE TEMPORAL BONE INTERPOSED BY AN www.indiandentalacademy.com ARTICULAR DISC IN BETWEEN.
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  • An Amphibian jawarticulation b/w the terminal portion of Meckels cartilage & the palatoquadrate bar. Teeth are confined to the dentary bone A Reptile jaw- dentary is of increased size Fossil Mammal like Reptileenlarged dentary & has coronoid process Mammals- Articulation of dentary with the temporal bone & www.indiandentalacademy.com constitutes part of inner ear.
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  •  Embryology – Cranial most part –enlarges Two big bulging in the ventral aspect of the embryo. Depression - Stomatodeum Neural groove – 21st day Closure of neural tube – 23rd www.indiandentalacademy.com day
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  • 1st arch – Mandibular arch 2nd arch – Hyoid arch 3rd arch 4th arch 6th arch No Names 5th arch – Disappears soon after formation. www.indiandentalacademy.com
  •  1st – Meckels cartilage , incus & malleus , also ant. lig. of malleus & Sphenomandibular lig  2nd - Stapes , Styloid process , Stylohyoid lig , Smaller cornu of hyoid , Superior part of body of hyoid.  3rd – Greater cornu of hyoid bone , lower part of the body of hyoid bone.  4th & 6th – Cartilages of larynx. www.indiandentalacademy.com
  •  4th to 28 weeks www.indiandentalacademy.com
  • Development of TMJ →  Acc to Baume, temporomandibular articulation originate from two different blastema.  The Condylar blastema & the Temporal blastema.  Condylar blastema –(primodium of the mandible) - condylar cartilage - the aponeurosis of the external pterygoid muscle - the disc - the capsular elements of the lower joint. www.indiandentalacademy.com
  • Temporal Blastema – - Articular structures of the upper level  Condylar blastema forms at the distal end of the primordium of the mandible.  The mandible begins to ossify – 7th week of fetal life / 19mm stage of fetal development.  22mm stage / 8th week – bone laid down in a platelike form lateral to Meckels cartilage. www.indiandentalacademy.com
  • Horizontal section of developing mandible 8th week IU Meckels cartilage extends from the Cartilaginous otic capsule to the midline symphysis bone of the mandible is forming in the membrane Tongue Meckels cartilage www.indiandentalacademy.com
  •  Phylogenetically , the developing middle ear in primates & especially the humans was the initial jaw joint of the vertebrates  In the middle ear region that the malleus & probably the incus develop as posterior extensions of Meckels cartilage.  The intermediate portion of Meckels cartilage disappears, but its sheath remains to persist in the form of anterior malleolar ligament & the sphenomandibular lig. www.indiandentalacademy.com
  • A -relationship b/w A -Anterior malleolar lig. mandible & middle ear. B -Malleus B -reference to C - Incus www.indiandentalacademy.com Meckels cartilage.
  •  24mm stage embryo, the pterygoid & masseter muscles have differentiated.  At the superior border of the external pterygoid muscle & just below to the masseter muscle, a layer / bulk of mesenchyme tissue which is the analogue of articular disc.  28mm stage the middle ear ossicles are fully formed in true cartilage & malleus is continuous with the Meckels cartilage. -Articular disc & external pterygoid tendons are attached to the malleus. www.indiandentalacademy.com
  •  11th week – condylar cartilage becomes evident, located at the upper end of the posterior border of developing mandible.  30mm stage embryo – articular surface faces directly lateral, it is parallel to the articular disc as well as to the articular surface of the zygomatic process of the temporal bone.  50mm stage – condylar cartilage shapes the articulating surface of the condyle in a hemisphere. www.indiandentalacademy.com
  • - Articular disc has flattened & the plane of the articular surfaces has undertaken a shift of 450 - 55mm stage – condylar head produces an osseous head which matures into condylar cartilage by 65mm stage – Baume. - 85mm stage – ossification of the cartilage begins, growth center of the mandible. - joint cavity formation is evident as the www.indiandentalacademy.com
  •  Inferior portion of the joint cavity takes the shape of a distinct cleft.  13th week – the lower joint cavity is well formed around the superior surface of the condyle, so as the upper part.  15th week – vascular mesenchyme of the condylar cartilage can be seen breaking down. - both joint cavities are formed. www.indiandentalacademy.com
  •  At 155mm stage – differentiation continues anteriorly to arrive at a point of full articulation.  190mm stage – all the elements of the joint are fully formed.  Baume, full differentiation of all articular elements by 4th fetal month. www.indiandentalacademy.com
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  • 14 weeks of Human Fetus Parietal bone Occipital Frontal bone Squamous Part Secondary Secondary condylar coronoid cartilage Cartilage Ramus www.indiandentalacademy.com Maxilla
  •  8th – 10th weeks IU – proliferation & histodifferentiation takes place & condyle assumes its mature morphogenic pattern. Also 1st evidence of temporal bone  12th – 14th week IU – formation of articular disc  22nd week IU – both articular eminence & the glenoid fossa are well formed  Meckels cartilage plays no role in actual dev of TMJ, acts as a frame work / scaffold for the dev mandible.  Ramus formed of membranous bone & endochondral bone formation at the head of the condyle.  Early attachment of muscles of mastication – 8th week.  Attachment of external pterygoid – 13th week.  Masseter muscle attachment – 14th week. www.indiandentalacademy.com
  •  Joint Innervation –  Kitamura; - branches of Auriculotemporal nerve, masseter nerve, & the posterior deep temporal nerve Branches of Mandibular portion of Trigeminal N.  4th fetal month – nerve fibers may be observed in the articular capsule www.indiandentalacademy.com
  •  5th month – appear to reach the disc.  6th month – widest distribution over the condyle & within the disc.  Localization & distribution of nerve fibers at joint margins.  Nerve fibers in capsule innervate the synovial membrane of the joint as well. www.indiandentalacademy.com
  •  Du Brul; - the key relationship b/w jaw & ear dysfunction lies in the embryological development of the neural patterns of the TMJ. - demonstrated that the nerve to the internal pterygoid muscle also sends a branch to tensor tympani muscle (moves the malleus)  He states unequivocally that, “ Here in lies the key to the relationship b/w jaw & ear dysfunctions sometimes plaguing modern man along with the deteriorating of other parts of jaw & dental apparatus” www.indiandentalacademy.com
  • A – Mandible at birth B – At 6 years Lateral View C – In an Adult www.indiandentalacademy.com
  • Occulsal View A- At birth B- At 6 yrs C- Adult www.indiandentalacademy.com
  • MUSCLES OF MASTICATION - MASSETER - TEMPORALIS - LATERAL PTERYGOID -MEDIAL PTERYGOID www.indiandentalacademy.com
  • INTRODUCTION  Moves the mandible during chewing and speech.  These are SKELETAL, VOLUNTARY muscles.  Consists of - Masseter - Temporalis - Lateral Pterygoid - Medial Pterygoid - Buccinator (accessory /5th muscle) - Ant. belly of digastric, www.indiandentalacademy.com geniohyoid,mylohyoid,
  • MUSCLES OF MASTICATION www.indiandentalacademy.com
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  • DEVELOPMENT  It develops from the mesoderm of the 1st PHARANGIAL ARCH. www.indiandentalacademy.com
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  • MASSETER  Quadrilateral muscle that covers lateral surface of the mandible.  Has 3 layers: superficial, middle & deep.  Multipinnate arrangement of fibers www.indiandentalacademy.com
  • LAYERS ORIGIN FIBERS INSERTION SUPERFICIAL: ANT.2/3 OF LOWER BORDER ZYGOMATIC ARCH & ZYG. PROCESS OF MAXLLLA. - PASS DOWNWARDS & BACKWARDS AT 45º LOWER PART OF LATERAL SURFACE OF MAND. MIDDLE:   ANT. 2/3 OF DEEP SURFACE & POST. 1/3 OF LOWER BORDER OF ZYG. ARCH.   - VERTICALLY & DOWNWARDS.   MIDDLE PART OF RAMUS DEEP:   DEEP SURFACE OF ZYG. ARCH UPPER PART OF -   LAYERS ARE 3 SEPERATED BY AN RAMUS AND CORONOID www.indiandentalacademy.com NERVE ARTERY & A
  • TEMPORALIS  FAN shaped muscle. Fills the Temporal Fossa. MUSCLE TEMPORALIS ORIGIN FIBERS CONVERGE & PASSES THROUGH GAP DEEP TO ZYG. ARCH www.indiandentalacademy.com TEMPORAL BONE AND FASCIA INSERTION MARGIN & DEEP SURFACE OF CORONOID - ANT. BORDERS OF RAMUS OF MAND. -
  • LATERAL & MEDIAL PTERYGOID LATERAL PTERYGOID: It is a short & conical muscle. Has upper & lower head. MEDIAL PTERYGOID: Quadrilateral muscle Has superficial & deep head www.indiandentalacademy.com
  • LATERAL PTERYGOID ORIGIN FIBERS INSERTION UPPER (SMALL) FROM INFRATEMPORAL SURFACE & CREST OF G.WING OF SPHENOID RUN BACKWARDS & LATERALLY. CONVERGE FOR INSERTION PTERYGOID FOVEA (CONDYLAR NECK)   LOWER (LARGER) LATERAL SURFACE OF LATERAL PTERYGOID PLATE   ANT. MARGIN OF ARTICULAR DISC & CAPSULE OF TMJ. MEDIAL PTERYGOID ORIGIN FIBERS INSERTION SUPERFICIAL (SMALL) TUBEROSITY OF MAXILLA & ADJOINING BONE DOWNWARDS, BACKWARDS & LATERALLY MEDIAL SURFACE OF ANGLE & RAMUS OF MANDIBLE DEEP (LARGE) MEDIAL SURFACE OF   LATERAL PTERYGOID   PLATE & ADJ.   PROCESS OF   PALATINE BONE   www.indiandentalacademy.com   BELOW & BEHIND MAND. FORAMEN & MYLOHYOID GROOVE
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  • SUPPLIES: MUSCLE ARTERY VEIN NERVE MASSETER MASSETRIC.A. (II PART OF MAXILLARY A.) RESPECTIVE VEIN MASSETRIC NR. (BR.OF ANT. DIV.OF MAND.NR) TEMPORALIS SUP. TEMPORAL A. LATERAL PTERYGOID LAT. PTERYGOID. (II PART OF MAXILLARY A.) MEDIAL PTERYGOID MED. PTERGOID. (II PART OF MAXILLARY A.) PTERYGOID VENOUS PLEXUS DEEP TEMPORAL (BR.OF ANT. DIV.OFMAND.NR) MAXILLARY VEIN LAT. PTERYGOID (BR.OF ANT. DIV.OF MAND.NR) RETROMANDIBULAR VEIN MED. PTERYGOID (BR. OF MAIN TRUNK OF MAND. NR.) www.indiandentalacademy.com
  • SUPPLIES: MUSCLE ARTERY VEIN NERVE MASSETER MASSETRIC.A. (II PART OF MAXILLARY A.) RESPECTIVE VEIN MASSETRIC NR. (BR.OF ANT. DIV.OF MAND.NR) TEMPORALIS SUP. TEMPORAL A. LATERAL PTERYGOID LAT. PTERYGOID. (II PART OF MAXILLARY A.) MEDIAL PTERYGOID MED. PTERGOID. (II PART OF MAXILLARY A.) PTERYGOID VENOUS PLEXUS DEEP TEMPORAL (BR.OF ANT. DIV.OFMAND.NR) MAXILLARY VEIN LAT. PTERYGOID (BR.OF ANT. DIV.OF MAND.NR) RETROMANDIBULAR VEIN MED. PTERYGOID (BR. OF MAIN TRUNK OF MAND. NR.) www.indiandentalacademy.com
  • ELEVATION MASSETER MEDIAL PTERYGOID TEMPORALIS RETRACTION PROTRACTION DIGASTRIC GENIOHYOID LATERAL PTERYGOID MYLOHYOID DEPRESSION www.indiandentalacademy.com
  • Temporomandibular joint proper www.indiandentalacademy.com
  • The three major skeletal components that make up the masticatory system :  Maxilla  Mandible  Temporal bone www.indiandentalacademy.com
  • Temporal bone  A- mandibular fossa  B- external acoustic meatus  C- articular eminence  D- zygomatic process  E- tympanic plate  F- petrosquamous fissure www.indiandentalacademy.com
  • A- body A- genial spine (tubercles) B- ramus B- internal oblique ridge C- incisive fossa C- attach. area for medial pterygoid D- mental foramina D- temporal crest E- angle E- retromolar triangle F- external oblique line F- mandibular foramina G- coronoid process G- lingula H- condyle H- mylohyoid groove www.indiandentalacademy.com I- mental tubercle I- digastric fossa
  •  Condyle LP- lateral pole MP- medial pole pterygoid fovea www.indiandentalacademy.com
  • 1450  line drawn through the centers of the poles of the condyles, usually extends medially & posteriorly towards the anterior border of the foramen magnum. www.indiandentalacademy.com
  • Total medio-lateral length – 15 – 20 mm The anteroposterior width – 8 – 10 mm The articulating surface of the condyle extends both anteriorly & posteriorly to the most superior aspect of the condyle. Posterior articulating surface is greater than anterior surface & is quite convex anteroposteriorly & only slightly convex www.indiandentalacademy.com
  •  HISTOLOGY OF TMJ - Histologically the appearance varies with age, due to presence of secondary cartilage. - This cartilage appears about 10th month IU & remains as a zone of proliferating cartilage until about the later half of the second decade of life. - The condyle of the young child is not lined by a distinct layer of compact bone as is that of the adult. www.indiandentalacademy.com
  • A- fibrous articular layer B- cell rich proliferative layer C- hypertrophic condrocytes of the secondary cartilage D- woven bone being deposited around E- a template of calcified cartilage F- marrow space -multinucleated osteoclast - osteoblast layer www.indiandentalacademy.com depositing bone on
  • A – head of adult condyle centre B – lower part of intraarticular periphery disc & lack of bone A – collagen fibers at the B – regularly aligned at C – larger marrow spaces www.indiandentalacademy.com a layer of compact
  •  Histology of articular surfaceA – condyle head B – fibrous articular surface zone C – cellular rich zone D – fibrocartilagenous zone E – zone of calcified cartilage F – lower joint space www.indiandentalacademy.com G – intra articular space
  •  Articular disc - Composed of dense fibrous connective tissue - Extreme periphery of the disc , is innervated Sagittal plane – AB- anterior border PB- posterior border IZ- intermediate zone www.indiandentalacademy.com
  • Anterior view – the disc is slight thicker medially than laterally. LP- lateral pole MP- medial pole www.indiandentalacademy.com
  • -Sagittal section of the intra- - Adult intra articular disc articular disc of a neonate - shows sparse distribution -presence of numerous of cells fibroblasts. - rounded www.indiandentalacademy.com cartilage -like cells
  • ACL- anterior capsular lig. IC- inferior joint cavity muscles IRL- inferior retrodiscal lamina SC- superior joint cavity pterygoid AS- articular surface ILP- inferior lateral pterygoid RT- retrodiscal tissues SLP- superior lateral muscles SRL- superior retrodiscal lamina www.indiandentalacademy.com ELASTIC COLLAGENOUS
  •  The articular disc is attached to the capsular lig. ,not only anteriorly & posteriorly, but also medially & laterally; this attachment divides the joint into ; a) the upper cavity [superior cavity] b) the lower cavity [inferior cavity]  Upper is bordered by, the mandibular fossa & the superior surface of the disc.  Lower is by, the mandibular condyle & the inferior surface of the disc. www.indiandentalacademy.com
  •  Specialized endothelial cells forms a synovial lining surrounding the internal surface of the cavities.  This lining along with a specialized synovial fringe located at the anterior border of the retrodiscal tissues, produce synovial fluid. Synovial Fluid – i) metabolic requirements to the non-vascular articular surfaces of the joint. ii) lubrication during function, reducing friction. www.indiandentalacademy.com
  •  Lubrication – i) Boundary lubrication ii) Weeping lubrication  Boundary lubrication – -when the joint moves, the synovial fluid is forced from one area of the cavity to another. -prevents friction & is the primary mechanism of joint lub.  Weeping lubrication – -the ability of the articular surfaces to absorb a small amount of fluid. -forces during function drive a small amount of www.indiandentalacademy.com fluid in & out of the articular tissues, helps in metabolic exchange.
  •  Compressive forces release fluid & prevents sticking of articular tissues.  Weeping eliminates friction in compressed but not moving joint.  But prolonged compressive forces will exhausts this supply leading to deleterious effects. www.indiandentalacademy.com
  • Crimping of collagen fibers in the intra articular disc is indicative of tensional loads. About 2/3rd s of the glycosaminoglycan is chondroitin sulphate & 1/3rd is dermatan sulphate, traces of hyaluronan & heparin sulphate. www.indiandentalacademy.com
  •  Innervation of TMJ – - The trigeminal nerve , that provides both motor & sensory innervation to the muscles that control it. - Afferent innervation – branches of the mandibular nerve. - Also by auriculo-temporal nerve as it leaves the mandibular nerve behind the joint & ascends laterally & superior to wrap around the posterior region of the joint. www.indiandentalacademy.com - Additional nerves – temporal & masseteric .
  • RUFFINI Posture (proprioception) PACINI GOLGI FREE Dynamic & static balance (capsule) Dynamic Movement (mechanoreception) accelerator (capsule) Static Protection (mechanoreception) (ligament) Pain Protection (nociception) (joint) www.indiandentalacademy.com
  •  Vascularization – - predominantly ; artery artery artery i) from posterior- superficial temporal ii) from anterior- middle meningeal iii) from inferior- internal maxillary iv) others ; - the deep auricular - anterior tympanic - ascending pharyngeal arteries - condyle, receives through its marrow spaces by “feeder vessels” from inferior alveolar artery. www.indiandentalacademy.com
  • LIGAMENTS  Made up of collagenous connective tissues having particular lengths & they do not stretch.  Act as passive restraining devices to limit & restrict border movements.  The three functional ligs ; i) the collateral lig ii) the capsular lig iii) the temporomandibular lig www.indiandentalacademy.com
  • AD- Articular disc CL- Capsular ligament IC- Inferior joint cavity SC- Superior joint cavity LDL- Lateral discal lig www.indiandentalacademy.com
  •  Collateral (discal ligaments) : - Attaches the medial & lateral borders of the articular disc to the poles of the condyles. - Divides the joint mediolaterally into the superior & inferior cavities. - True ligs , do not stretch & restricts movement of the disc away from condyle. - Responsible for hinging movement of the TMJ. - Have both vascular as well as innervation , providing information regarding joint position & movement. www.indiandentalacademy.com - Strain on these ligs produces pain.
  • Capsular ligament - surrounds & encompasses the entire TMJ. - superiorly to the temporal bone along the borders of the articular surfaces of the mandibular fossa & articular eminence. - inferiorly – neck of the condyle - resist any medial, lateral / inferior forces that tend to separate / dislocate the articular surfaces. - helps to retain synovial fluid & provides proprioceptive feedback. www.indiandentalacademy.com
  • Temporomandibular (Lateral) ligament  IHPInner horizontal portion  OOPOuter oblique portion Oblique portion – resists excessive dropping of the condyle - normal opening of the mouth. - wider mouth opening- the condyle moves downwards & forward across the articular eminence. www.indiandentalacademy.com - unique limited rotational opening is found only in
  • - in erect postural position & with a vertically placed vertical column, continued rotational opening movement would cause the mandible to impinge on the vital sub-mandibular & retromandibular structures of the neck. Inner horizontal portion ; - limits the posterior movement of the condyle & disc. - protects the retrodiscal tissues from trauma. - also protects the lateral pterygoid muscle from over-lengthening / extension - trauma to the mandible – neck of the condyle will fracture before the retrodiscal tissues are www.indiandentalacademy.com severed / before the condyle enters the middle
  •  Accessory ligs ; i) the sphenomandibular lig ii) the stylomandibular lig iii) the pterygomandibular raphe iv) the retinacular lig www.indiandentalacademy.com
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  • BIOMECHANICS OF TMJ – Can be divided into two system: 1) One joint system;  Tissues surrounding the inferior synovial cavity (condyle & the articular disc)  Only physiologic movement is rotation of the disc on the articular surface of the condyle – condyle-disc complex.  Responsible for rotational movement in the TMJ. www.indiandentalacademy.com
  • 2) condyle-disc complex functioning against the surface of mandibular fossa;  Free sliding movement possible, in the superior cavity.  This movement occurs when the mandible is moved forward – translation. Articular disc is not a meniscus.  Meniscus – is a wedge shaped crescent of fibrocartilage attached on one side to the articular capsule & unattached on the other side,extending freely into the joint spaces. - functions passively to facilitate movement. www.indiandentalacademy.com
  •  The articular surfaces of the joint is maintained by constant activity of the muscles that pull across the joint, primarily the elevators. (even in resting stage in a mild tonus)  Increase in intra articular pressure holds the joint.  Width of the disc varies with the intra articular pressure. - low (closed rest position) – widens. - high (clenced) – space narrows. www.indiandentalacademy.com
  • Posterior border of the articular disc – retrodiscal tissues.  Opening of the mandible – the superior retrodiscal tissue gets stretched, creating increased force to retract the disc.  Mandible moves into full forward position & during its return – retraction force of the sup. retrodiscal tissue holds the disc rotated as far posteriorly on the condyle as the width of the articular disc permits.  The sup retrodiscal tissue – only structure www.indiandentalacademy.com capable to retract the disc posteriorly on the
  • Anterior border of the disc –  attachment of the superior lateral pterygoid muscle. (also attached to the neck of the condyle)  Helps in protraction of the disc, dual attachment doesn’t allow the muscle to pull the disc through the discal space  The inferior lat pterygoid when protract the condyle forward, the superior fibers is inactive – disc is not moved forward with the mandible.  The superior lat pterygoid is activated only in conjunction with elevator muscles. (closure / power strokes)www.indiandentalacademy.com
  •  During translation, the combination of disc morphology & interarticular pressure maintains the condyle on the intermediate zone – disc is forced to translate forward with the condyle.  When the morphology of the disc has been altered, the ligamentous attachment of the disc affects joint function. Things to remember :  ligaments; -do not actively participate in normal functioning of the TMJ -act as guide wires,restricting & permitting some movements -restrict joint movements both by mechanical & through neuromuscular reflex activity. www.indiandentalacademy.com
  •  Ligaments do not stretch (ability to return to its original length) - traction force- elongates, if elongates then often the function is compromised.  Articular surfaces of the TMJs must remain in constant contact (the elevators ; temporal, masseter, & medial pterygoid) www.indiandentalacademy.com
  •  Mandibular rest position : -Physiologic rest position → muscle tonus of the elevator muscles → myostatic reflex (affected by the wt. of the mandible) -Rest position → 1.3 – 3.0 mm of interocclusal clearance (freeway space) - Changes with head posture & muscle tonus. -Varies with head position, total body posture, functional activities, fatigue, time of day, age & emotional tension. www.indiandentalacademy.com
  • VERTICAL DIMENSION OF OCCLUSION  Increase in VDO → increased activity in the elevator muscles, with pain & resulting in dysfunction. Akagawa et al; - within interocclusal clearance displayed → transient acute inflammation in the deep & superficial masseter muscle. - more than 1mm → early acute inflammation to muscle fiber regeneration in the deep masseter, with a lesser degree in superficial masseter & ant. temporal muscle. Carlson et al; www.indiandentalacademy.com - VDO can be altered by using bite planes, without
  • Examination of TMJ in ORTHODONTIC CLINICS  Posture of the clinician & patient  Palpation – in closed, at rest & various open position  Deviation should be noted  Crepitus / abnormal sound  Palpation of the neck & sub mandibular area  Speech evaluation www.indiandentalacademy.com
  • Palpation in •closed •open •wide open www.indiandentalacademy.com
  • Standards for TMJ evaluation: pediatric dentistry 1989- 11(4);330 History ; 1) Does your child report any pain during chewing / while opening the mouth wide? 2) Child report any discomfort in the jaws upon awakening 3) Child complains of headache 4) Any history of trauma to the jaws or neck region? 5) History of allergies? 6) Jaw click / lock upon opening? www.indiandentalacademy.com
  • +ve history – pain manifestation, stress, balanced diet, sleeping posture  Clinical examination :  gentle & cautious palpation of muscles of mastication. - for trigger points - rated, 0 – no pain ; 1- tenderness ; 2 – definite pain ; 3 – evasive action. www.indiandentalacademy.com
  •  Range of movement : -maximum opening & lateral excursions -widest opening – 40mm -anterior bite depth – 34mm -overbite – 6mm  Click : -early, late, or both on opening.  Radiographic examination & advances : - transcranial radiographs / tomograms - MRI & arthrograms www.indiandentalacademy.com
  • Temporomandibular disorders in children: Jeffrey P.Okeson  Are TM disorders a problem in children ?  How TM disorders treated in children ?  Can early treatment prevent TM disorders ? www.indiandentalacademy.com
  •  Are TM disorders a problem in children? -epidemiologic studies – 10-18 yrs. -studies place the findings into two categories via; a) symptoms b) signs -common in young population – few complain  How are TM disorders treated in children? -Ingerslev – conservative & reversible -occlusal appliance - < 2 months www.indiandentalacademy.com
  • Two major categories : a) masticatory b) disc- interference / internal dearangements Can early treatment prevent TM disorders? -etiology is of paramount importance -occlusal condition -no scientific evidence www.indiandentalacademy.com
  • Prevalence of TMJ disorders in children Eup J.orthod 14;152161:1992  A longitudinal study,for the signs & symptoms of CMD in 12-15 yr old individuals.  “during this period there is an increased prevalence of S/S of CMD. In particular true for headache & joint sounds. www.indiandentalacademy.com
  • Heritability of TMJ disorder signs & symptoms J dent.res     79(8):1573-1578,2000. Genetic variance & environmental variances This study results suggest that neither shared genes nor the family environment accounts for much of variance in TMJ related s/s & oral habits. TMJ-pain was reported by 8.7% of the twins – Lipton et al 1993. Joint noises & locking in these twins were also about as prevalent as in non-twin population.  Pain reporting in particular is influenced by mood, www.indiandentalacademy.com stress, learned behaviors, physiological pain
  •  They concluded that i) Genetic factor do not influence joint disorders manifesting pain. or ii) Pain perception factors are non-genetic, supported by twin study of pain threshold – Mac Gregor et al ;1997. So till date no study has substantial evidence of any genetic relation of joint pain. www.indiandentalacademy.com
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  • HARD TISSUE IMAGING: •Panoramic projection •Specialized TMJ radiography techniques: •Trans cranial •Trans pharyngeal • Trans orbital •Submento vertex (basal) projection •Conventional tomography •Computerized tomography (CT SCAN) SOFT TISSUE IMAGIMG: •Magnetic Resonance Imaging (MRI SCAN) •Arthrography www.indiandentalacademy.com
  • TRANS PHARYNGEAL TRANS ORBITAL TRANS CRANIAL www.indiandentalacademy.com
  • OPG CONVENTIONAL TOMOGRAPHY www.indiandentalacademy.com
  • ARTHROGRAPHY MAGNETIC RESONANCE IMAGING www.indiandentalacademy.com
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  •  TMJ disorders – (intra capsular disorders)  Physical examination- inspection for the pattern & the presence of noise / deviation on opening  Normal vertical opening – width of three fingers  Diff b/w maximal pain –free opening & maximal opening with pain  Patient is asked to point the area of pain  Muscle of mastication palpated  Magnitude of opening ; Maximal incisal opening of less than 20-25mmmuscle spasm Periauricular pain beginning at 25-30mm- TMJ www.indiandentalacademy.com capsulitis
  •  Lateral movements ;  > 5mm –well functioning TMJ  normal lateral but painful vertical opening – muscle spasm  1 min clench test : - Tongue blade placed unilaterally on the posterior teeth –if hyperactivity muscle – ipsilateral pain - Capsulitis –pain on the contralateral side - Placed bilaterally – if pain relieved – splint therapy.  TMJ noises : www.indiandentalacademy.com -click – 2-3 trials indicates disc displacement
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  •  TMJ tenderness ;  Patient open slightly bringing the condyle & disc from under the zygomatic arch.  Retro discal area palpated – wide open mouth  The surface posterior to the condyle is pressed  Little fingers can be placed in the external auditory canal  Lateral / posterior sensitivity – either capsulitis / www.indiandentalacademy.com synovitis
  •  Joint inflammation ; -synovial, capsular / retrodiscal tissues – capsulitis or synovitis -due to infection, trauma, systemic diseases, articular surface degeneration / disk displacement -preauricular pain -episodic swelling with occlusal changes can occur.  TMJ dislocation (open lock) -subluxation -painful -jaw manipulation www.indiandentalacademy.com
  •  Treatment of joint disorders –  Patient’s education  Pain free diet  Therapeutic exercises to rehabilitate the joint  Anti-inflammatory drugs &muscle relaxants  Physical therapy –  Heat / ice massage  Gentle range of motion exercises with in the pain tolerance.( 6 times a day for 30-60 secs )  Joint shouldn’t hurt more than 10mins after exercise  Night time splint – reduces forces on the joint. www.indiandentalacademy.com
  •  Night guard, controls parafunctional habit, temporary stabilizes an uneven occlusion – allows the joint to rest.  Should have a flat plane – opening the bite several mm.  Soft night guard is given for children with developing occlusion / mixed dentition. www.indiandentalacademy.com
  •  Painful click – mandibular orthopedic repositioning appliance www.indiandentalacademy.com
  •  Extra capsular disorders Acute disorders :  Myositis- due to infection / injury  Protective muscle spinting – constriction of muscles to avoid pain, pain in function  Myospasm (acute trismus) – involuntary, sudden, tonic contraction of muscles www.indiandentalacademy.com
  • Chronic disorders :  Myofacial pain – -most common in children -jaw function aggravates headache. -localized tender / trigger points (active / passive) -tender spots may produce characteristic pattern of referred pain. www.indiandentalacademy.com
  • -can be caused by postural problems, parafunctional habits, psychological disorders, stress & trauma. -pain is reduced / eliminated with anesthetic injection into active trigger points, or a spray & stretch procedure with fluormethane spray. -long term - elimination of the contributing factor. -analgesics, muscle relaxants, behaviour modification & home rehabilitation & physical therapy. www.indiandentalacademy.com
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  • “ The clinician who only looks at occlusion is missing as much as the clinician who never looks at occlusion. ” OKESON www.indiandentalacademy.com
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  • References :  Management of Temporomandibular Disorders & occlusion -JEFFREY P.OKESON  Diseases of the temporomandibular apparatus - DOUGLAS H. MORGAN  Pediatric oral & maxillofacial surgery - L B.KABAN  Oral anatomy, histology & embryology - BERKOVITZ  DCNA –vol.27,no.3,july 1983  Bell’s orofacial pain -5th ed. www.indiandentalacademy.com
  • •Orthodontics & the temperomandibular joint: where are we? Part 1: orthodontic treatment and TMJ disorders. The Angle Orthodontist:vol. 68, no.4 -295- 304 •Orthodontics & the temperomandibular joint: where are we? Part 2:functional occlusion,malocclusion,& TMD. The Angle Orthodontist:vol. 68, no.4 -305- 318. •Prevalence of TMJ disorders in children :Eup J.orthod 14;152-161:1992 •Heritability of TMJ disorder signs & symptoms: J dent.Res 79(8):1573-1578,2000. •Standards for TMJ evaluation: pediatric dentistry 1989www.indiandentalacademy.com 11(4);330
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